Issue #22078 has been reported by hsbt (Hiroshi SHIBATA). ---------------------------------------- Bug #22078: mswin: `gmp.h` not found with `--with-opt-dir` on Ruby 3.3/3.4 https://bugs.ruby-lang.org/issues/22078 * Author: hsbt (Hiroshi SHIBATA) * Status: Open * Backport: 3.3: REQUIRED, 3.4: REQUIRED, 4.0: DONTNEED ---------------------------------------- On mswin builds, `win32/Makefile.sub` builds `XCFLAGS` without `XINCFLAGS`, so the include path written by `configure.bat --with-opt-dir=...` never reaches `cl.exe` and `#include <gmp.h>` cannot be resolved. `master` and `ruby_4_0` are fixed by https://github.com/ruby/ruby/commit/13c64a8a20, but neither `ruby_3_4` nor `ruby_3_3` has it. How it surfaces differs between the two: - `ruby_3_4`: `win32/setup.mak` auto-enables GMP whenever gmp is present, so the build tries to use it and fails on the missing `gmp.h`. - `ruby_3_3`: `win32/setup.mak` only enables GMP when `--with-gmp` is explicitly passed. Without the flag the build passes but GMP is never used; with the flag, it fails the same way as 3.4. -- https://bugs.ruby-lang.org/